1. Field of the Invention
The present invention relates to an antenna with pseudo toric cover having two reflectors for transmitting and /or receiving microwaves.
2. Description of the Prior Art
Numerous radar applications require an antenna capable of providing rotating beams. It is known to obtain such rotating beams by means of rotating antennae; these have a number of well known disadvantages, particularly the lack of flexibility, which has leg to developing static antennae where the movement of the beam is provided electronically.
Different static antennae constructions are known, among which can be mentioned a structure formed of an assembly of antennae in the form of a slab, disposed in the shape of a truncated pyramid. The cover obtained is semi spherical and operation is satisfactory. Its drawback is however a high cost price . The so called dome antenna is also known which is formed by a network of radiating elements providing sweeping of the beam along a cone of limited angle, of the order of 90.degree., covered by a hemispherical dome, which comprises elements phase shifting the radiation passing therethrough, so that the sweep angle of the beam outside the dome is equal to 180.degree.. The advantage of this structure is particularly to reduce the number of active elements required with respect to the preceding construction, but it has a certain number of drawbacks among which can be mentioned the complexity in manufacturing the dome including phase shifters, the volume of the resulting antenna and the losses occurring by reflection on the wall of the dome.
An object of the present invention is to provide a static antenna avoiding these disadvantages by using a double reflection system, the reflectors being passive and of revolution, which is relatively simple and inexpensive to manufacture.